My suggestion was from the plants, but you asked about testing the leftover mix you have. I'd say do both.
See this:
You'll know how well you did if the pH of the unused mix you have around 5.8.
420 Magazine's Official Girl Scout Cookies Comparative Grow By Beez0404
- Thread starter beez0404
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- #322
How do I test the unused medium? Same way?
Same way.
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- #324
Well I guess a test of character of a man is his willingness to admit his homemade medium has a pH of 7.34 unused and the used medium has a pH of 6.94
So I guess for the unused portion I add more sphagnum peat moss, wet it in and re-test the pH in a few days or a week?
What can I do for the GSC girls? How do I lower the pH in those pots?
So I guess for the unused portion I add more sphagnum peat moss, wet it in and re-test the pH in a few days or a week?
What can I do for the GSC girls? How do I lower the pH in those pots?
You never know until you test!
Source
Also this from @Virgin Ground
And this:
"High pH soil may be acidified by adding elemental sulfur.Granular elemental sulfur is the safest, least expensive but slowest acting product. Sulfur is transformed by soil bacteria to sulfuric acid which will neutralize soil alkalini-ty.The pH change is gradual over time. It can take up to a year to record a change in the soil pH. Check pH at the same time each year, as soil pH varies seasonally. Due to the total amount of hydroxl ions present in alkaline soils, this is a never ending battle.As soon as the sulfur is "used up" pH will begin to return to original levels.Sulfur is useful for reversing the effects of high pH irrigation wa-ter or for changing soil pH in a small area.Aluminum sulfate and iron sulfate react quicker than ele-mental sulfur. However, they must be applied at a 5 to 6 times greater rate (Table 1) than sulfur. Do not apply more than 5 lbs per 100 square feet at any one time. Excessive amounts of these two sulfates can also injure plants."
Source
Under different circumstances I would suggest finding a nutrient that was higher in ammoniacal nitrogen, as that would lower the pH of the peat over a couple of weeks. That's what I did when my pH rose to the same range you're in. Then you could go back to the Rx Blend, which is almost entirely nitrate nitrogen.
Alternatively, you could just add some cal-mag if that's what it looks like it needs.
Will you be transplanting these before you flip?
"Soil pH can be reduced most effectively by adding elemental sulfur, aluminum sulfate or sulfuric acid. The choice of which material to use depends on how fast you hope the pH will change and the type/size of plant experiencing the deficiency. Sulfuric acid (commonly available as battery acid) is fast acting, but is very dangerous, and its use by home gardeners is not recommended. Green industry professionals however, occasionally use sulfuric acid to reduce soil pH around large, established specimen trees. Aluminum sulfate and elemental sulfur can be safely used by homeowners. Aluminum sulfate is faster acting than elemental sulfur because it is very soluble. The advantage of elemental sulfur is that it is more economical, particularly if a large area is to be treated."
Source
Also this from @Virgin Ground
And this:
"High pH soil may be acidified by adding elemental sulfur.Granular elemental sulfur is the safest, least expensive but slowest acting product. Sulfur is transformed by soil bacteria to sulfuric acid which will neutralize soil alkalini-ty.The pH change is gradual over time. It can take up to a year to record a change in the soil pH. Check pH at the same time each year, as soil pH varies seasonally. Due to the total amount of hydroxl ions present in alkaline soils, this is a never ending battle.As soon as the sulfur is "used up" pH will begin to return to original levels.Sulfur is useful for reversing the effects of high pH irrigation wa-ter or for changing soil pH in a small area.Aluminum sulfate and iron sulfate react quicker than ele-mental sulfur. However, they must be applied at a 5 to 6 times greater rate (Table 1) than sulfur. Do not apply more than 5 lbs per 100 square feet at any one time. Excessive amounts of these two sulfates can also injure plants."
Source
Under different circumstances I would suggest finding a nutrient that was higher in ammoniacal nitrogen, as that would lower the pH of the peat over a couple of weeks. That's what I did when my pH rose to the same range you're in. Then you could go back to the Rx Blend, which is almost entirely nitrate nitrogen.
Alternatively, you could just add some cal-mag if that's what it looks like it needs.
Will you be transplanting these before you flip?
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- #326
Nah, they'll be flipped in those 3 gallon pots. I'm almost positive that what I did was mix 20 gallons of medium with the amount of organic garden lime used for making 30 gallons. Now Shed, I'm an old uneducated non farming guy. If you just told me in black and white what I needed to do to lower the pH of the medium the GSC plants are in and to lower it accurately I missed it somehow. I understood aluminum sulfate is probably what I want to use but what is it? Where do I buy it? How much do I use and how do I use it?
Also, how do I lower the pH of the unused medium? Just add 10 gallons of peat moss and stir it in real good and check the pH in a week or 10 days?
Also, how do I lower the pH of the unused medium? Just add 10 gallons of peat moss and stir it in real good and check the pH in a week or 10 days?
I've never done a dunk in anything to lower the pH - I've only used different nutes - so I wish I had clearer instructions for you. I can only tell you what the concept is, and that's to infuse the medium with some aluminum sulfate by dunking it in a solution.
Barring that, your two options are to let it ride and do the best you can with some added supplements or differing amounts of the Rx Blend bottles, or to use another fertilizer that has more ammoniacal nitrogen, which will cause the roots to lower the pH naturally over a couple of weeks. I used GrowMore 20-10-20 orchid fertilizer from a local nursery (Amazon sells it too). $10 for a small container since you won't need much.
To lower the pH of the unused medium, add more peat and perlite and moisten the whole thing, give it a week and check again.
Barring that, your two options are to let it ride and do the best you can with some added supplements or differing amounts of the Rx Blend bottles, or to use another fertilizer that has more ammoniacal nitrogen, which will cause the roots to lower the pH naturally over a couple of weeks. I used GrowMore 20-10-20 orchid fertilizer from a local nursery (Amazon sells it too). $10 for a small container since you won't need much.
To lower the pH of the unused medium, add more peat and perlite and moisten the whole thing, give it a week and check again.
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- #328
How about if I add a tablespoon of this to my next feeding and see what it does?
- Thread starter
- #330
I hate to keep bugging you Matthew @Prescription Blend but it is now obvious that when making my homemade promix for the GSC girls I added the amount of lime needed for 30 gallons when I actually only mixed up 20 gallons so the pH of my medium is quite high. Anything you recommend using your products?
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- #331
You reckon we're talking it working in a week? A couple weeks? A month?
I wish I could tell you beez. The only folks I've helped with high pH in their mediums before were able to lower it by switching out the nutes for two weeks.
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- #333
Would it help to add stuff like cal-mag and turpinator to the mix?
Doesn't look like you have a potassium deficiency, so the Terp won't help. Cal-mag will help with the rust spots, but if you're willing to add both cal-mag and Terp, why not just change out nutes for a 2-3 waterings?
- Thread starter
- #335
Well the wife is holding the Kominsky Method waiting on me. I will address this further tomorrow morning. Thanks for all your help Shed.
Modest Grower
Well-Known Member
Loving the trouble shooting going on here and all the help. Unfortunately, I don't have much to offer but when I heard knock of promix I thought of Promix bee. The ladies look healthy so at least they will hang around while it is dialed in. Happy saturday!
All in all the plants look pretty good, so you might just want to stick with what you're doing now if the spots aren't spreading and they still look healthy. You could just keep your options in your back pocket for now.
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- #338
Today was feeding day for the GSC girls. This is what they were fed this morning. One gallon of well water with 30ml of Turpinator, 5 ml of Cal-Mag, 11 ml Core A and Core B, and 5ml of the other Prescription Blend nutrients. And finally I added a tablespoon of that sulfur. I watered to a good runoff and now we'll see what happens.
For the unused Faux ProMix outside in the tote I added 10 gallons of Canadian Sphagnum peat moss and 5 gallons of perlite. I also added a tablespoon of mycorrhizae and mixed that all together really well and then watered it in till it was nice and moist but not "wet". I'll check the pH in that outside tote in what 4 or 5 days?
For the unused Faux ProMix outside in the tote I added 10 gallons of Canadian Sphagnum peat moss and 5 gallons of perlite. I also added a tablespoon of mycorrhizae and mixed that all together really well and then watered it in till it was nice and moist but not "wet". I'll check the pH in that outside tote in what 4 or 5 days?
- Thread starter
- #339
Girl Scout Cookie update for today Day 55 post sprout.
Every time I walk by the plants I bend down the main and secondary branches. I removed maybe 4 leaves from each to open the side branching. When I get this pH issue under wraps these girls I think are going to take off. The @Weed Seeds Express GSC seeds are of good genetic quality. The @Prescription Blend will do a good job if I wasn't screwing things up. And that @Mars Hydro light is absolutely amazing. It is set at 75% of full power and I can rest my hand on the aluminum cross members they are so cool to the touch. The driver located outside the tent ay 75% of full power gets a little warm but again I can still hold my hand on it.
Every time I walk by the plants I bend down the main and secondary branches. I removed maybe 4 leaves from each to open the side branching. When I get this pH issue under wraps these girls I think are going to take off. The @Weed Seeds Express GSC seeds are of good genetic quality. The @Prescription Blend will do a good job if I wasn't screwing things up. And that @Mars Hydro light is absolutely amazing. It is set at 75% of full power and I can rest my hand on the aluminum cross members they are so cool to the touch. The driver located outside the tent ay 75% of full power gets a little warm but again I can still hold my hand on it.
They're looking good!
Give it a week.
We're gonna need a screenshot of your step counter.